White blood cells (leucocytes)White blood cells (leucocytes)Our bodies are exposed to bacteria ,viruses, fungi, many of these Our bodies are exposed to bacteria ,viruses, fungi, many of these

agents are capable of causing serious effects.Fourtunately ,our agents are capable of causing serious effects.Fourtunately ,our bodies have a special system to protect our bodies from these bodies have a special system to protect our bodies from these agent .this is composed of white blood cells and tissue cells these agent .this is composed of white blood cells and tissue cells these cell work together in cell work together in two different way to prevent disease :two different way to prevent disease :

1- By actually destroying invading agents by the process of 1- By actually destroying invading agents by the process of phagocytosis.and by forming, phagocytosis.and by forming, antibodies and sensitized antibodies and sensitized lymhocytes,onelymhocytes,one or both which destroy the invader. or both which destroy the invader.

White blood cellWhite blood cellLeucocyte are spherical living cells with nucleinand are capable of Leucocyte are spherical living cells with nucleinand are capable of

ameboid movementameboid movementTheir size is not uniform and is usually larger than the red cellsTheir size is not uniform and is usually larger than the red cellsAs no pigment is found in their cytoplasm ,they appear As no pigment is found in their cytoplasm ,they appear

coulerless ,they have no haemoglobulin.coulerless ,they have no haemoglobulin.In adult male there are normally 4.000-11.000 white blood cells/mm3In adult male there are normally 4.000-11.000 white blood cells/mm3According to the present or absence of granules in their cytoplasm According to the present or absence of granules in their cytoplasm

they are they are divide into:divide into:

1-1- GranulocytesGranulocytes Which have granules in their cytoplasm,and a Which have granules in their cytoplasm,and a

lobed nucleus. They are formed in the bone lobed nucleus. They are formed in the bone marrow.marrow.

NeutrophilsNeutrophils: They are highly phagocytic and : They are highly phagocytic and form 60-75% of leucocyteform 60-75% of leucocyte

EosinophilsEosinophils: these are slightly phagocytic and : these are slightly phagocytic and form 1-4% of leucocyte.form 1-4% of leucocyte.

Basophils:Basophils: these are not phagocytic and form these are not phagocytic and form 0-1% of leucocyte.0-1% of leucocyte.

II-Non granulocyteII-Non granulocyte.. They have no granules in They have no granules in the cytoplasm and have the cytoplasm and have two formtwo form::

Lymhocytes;Lymhocytes; These constitute 20-40% and are These constitute 20-40% and are not phagocytic.not phagocytic.

MonocytesMonocytes:they are highly phagocytic and :they are highly phagocytic and form2-8% of leucocytes.form2-8% of leucocytes.

Function of WBCsFunction of WBCs The most important function is defense against The most important function is defense against

microorganism and their toxins.microorganism and their toxins. Function of NeutrophilsFunction of Neutrophils (Microphages) (Microphages) They are highly phagocytic.They are highly phagocytic. They engulf microorganisms.They engulf microorganisms. They have the propertes of diapedesis and They have the propertes of diapedesis and

chemotaxis.chemotaxis. Diapedesis: Mean escape of a big leukocyte from Diapedesis: Mean escape of a big leukocyte from

a very narrow pore in the wall of the blood vessels. a very narrow pore in the wall of the blood vessels. in tissue space it moves by pseudopodia like in tissue space it moves by pseudopodia like ameba .ameba .

Chemotaxis: Mean movement of leukocyte toward Chemotaxis: Mean movement of leukocyte toward a source of certain chemical substances .a a source of certain chemical substances .a chemical substance called luecotaxin attracts chemical substance called luecotaxin attracts neutrophils towards the site of inflammation .neutrophils towards the site of inflammation .

Phagocytosis : phagocytes have enzymes Phagocytosis : phagocytes have enzymes (hydrogen peroxide) which digest the engulfed (hydrogen peroxide) which digest the engulfed organism.organism.

Functions of eosinpohils:Functions of eosinpohils: They are weak phagpcytic.They are weak phagpcytic. They are related to allergy or hypersensitivityThey are related to allergy or hypersensitivity They detoxify toxins and foreign proteins which increased in They detoxify toxins and foreign proteins which increased in

allergic condition .allergic condition . They release plasminogen needed for laysis and removal of blood They release plasminogen needed for laysis and removal of blood

clots by fibrinolysis.clots by fibrinolysis.

Functions of basophiles:Functions of basophiles: They are not phagocytic.They are not phagocytic. They secrete heparin ( anticoagulants)They secrete heparin ( anticoagulants) They are related to allergy.They are related to allergy.

Functions of lymhocytesFunctions of lymhocytes Formation of antibodies. It can also changed into plasma cell which Formation of antibodies. It can also changed into plasma cell which

is the main producer of antibodies.is the main producer of antibodies.

MonocytesMonocytes They are highly phagocytic.They are highly phagocytic. Tissue repair after inflammationTissue repair after inflammation Lymphocyte can changed into highly phagocytic monocytes but Lymphocyte can changed into highly phagocytic monocytes but

they are not phagocyttic itself.they are not phagocyttic itself.

Reticuloendothelial system Reticuloendothelial system (RES)(RES)

RES Consists of certain macrophages which is present in the RES Consists of certain macrophages which is present in the bone marrow, lymph nodes ,spleen ,liver.bone marrow, lymph nodes ,spleen ,liver.

Functions of R.E.S ; defenceFunctions of R.E.S ; defence 1-Formation of antibodies.1-Formation of antibodies. 2- Engulf forign particles,dust ,carbon.2- Engulf forign particles,dust ,carbon. 3-Destruction and digestion of micro-organism and protozoa.3-Destruction and digestion of micro-organism and protozoa. 2-Repair of tissue after inflammation2-Repair of tissue after inflammation They remove dead tissue & provide protein and fat needed They remove dead tissue & provide protein and fat needed

for repair and growth of damaged tissue .for repair and growth of damaged tissue . 3- Blood formation3- Blood formation R.E cells act as the origin of all blood cellsR.E cells act as the origin of all blood cells 4- Removal of old blood cells4- Removal of old blood cells from circulation from circulation

and formation of bile pigements.and formation of bile pigements. 5- storage of iron5- storage of iron needed for formation of new RBCs needed for formation of new RBCs

The spleenThe spleenIt is the largest lymphoid organ in the bodyIt is the largest lymphoid organ in the body

FunctionsFunctions; ; 1-Defense1-Defense; By formation of lymhocyte & plasma cell which play a role in ; By formation of lymhocyte & plasma cell which play a role in

immunity ,therfore in absence of spleen bacterial infection become more immunity ,therfore in absence of spleen bacterial infection become more common .common .

2- Blood formation2- Blood formation-Erytheropoiesis-Erytheropoiesis: in the middle third of intra uterine life , if bone marrow : in the middle third of intra uterine life , if bone marrow

destroyed ,spleen take this function.destroyed ,spleen take this function.Lymphopoiesis:Lymphopoiesis:Leucopoisis Leucopoisis Iron storage needed for erytheropoiesis.Iron storage needed for erytheropoiesis. 3- Removal of old blood cells and HB& bile 3- Removal of old blood cells and HB& bile

pigment formation.pigment formation. 4-Blood reservoir4-Blood reservoirThe splenic blood sinuses can accommodate a large quantity of circulating The splenic blood sinuses can accommodate a large quantity of circulating

blood this may reach of ¼ blood volume in animalsblood this may reach of ¼ blood volume in animalsThe stored blood is squeezed out of the spleen to the general circulation ,this The stored blood is squeezed out of the spleen to the general circulation ,this

occurs by contraction of muscles of spenic capsule supplied by occurs by contraction of muscles of spenic capsule supplied by sympathatic nerves ,the main stimulus is o2 lack which stimulate sympathatic nerves ,the main stimulus is o2 lack which stimulate symphathatic nervous contraction of the plain muscles of splenic symphathatic nervous contraction of the plain muscles of splenic capscule. capscule.

Lymph nodesLymph nodesLymph nodes are oval bodies , they lie between lymph Lymph nodes are oval bodies , they lie between lymph

vesselsvessels Functions of lymph nodes:Functions of lymph nodes: 1- filteration1- filteration The phagocytic cells in lymph nodes remove foreign The phagocytic cells in lymph nodes remove foreign

particle entering the nodes ,through the afferent lymph particle entering the nodes ,through the afferent lymph vessels (carbon particles in coal miners).vessels (carbon particles in coal miners).

2- Removal of bacteria2- Removal of bacteria::Bacteria enter lympsh nodes through the afferent lymph Bacteria enter lympsh nodes through the afferent lymph

vesselsvesselsincrease Macrophages in the node phagocyte the increase Macrophages in the node phagocyte the

bacteria.bacteria.These macrophages much in number during local These macrophages much in number during local

infection and thus the node enlarges,nodes in the neck infection and thus the node enlarges,nodes in the neck enlarge when the ears, nose or pharynx are infected.enlarge when the ears, nose or pharynx are infected.

3-Formation of lymphocytes3-Formation of lymphocytes 4- 4- Production of antibodiesProduction of antibodies : :